Biochemical Oxygen Demand (BOD) Determination

Excess organic matter is currently the main pollutant in aquatic ecosystems, and its source usually in effluents from industrial wastewater treatment processes and livestock activities. Organic matter that present in the natural environment significantly alters the level of organisms living in watercourses by reducing the level of dissolved oxygen. Dissolved oxygen (DO) is important for both aquatic plant and animal life, BOD measures the amount of oxygen consumed by the microbiological oxidation of organic matter present in water, and this test is often required in discharge permits, as it is a means of determining the degree of water pollution. BOD can be used to investigate the impact of organic matter in the natural environment, water eutrophication and its capacity for self-purification by reflecting the amount of dissolved oxygen consumed by bacteria in the oxidation of these substances. The BOD determination services of BOC Sciences enables an accurate assessment of the amount of biodegradable organic matter present in wastewater, sewage and polluted waters in the environment.

Features of BOD Determination

• Fast and efficient
• Low cost of analysis

Application of Our Services

Our BOD testing services can be applied to a variety of water quality monitoring processes: water treatment and reuse, waste water treatment plants (WWTP) operations, polluting industries, fish farming, aquaculture, hydroponic systems and environmental control - rivers, lakes, wetlands and beaches

• Adapt water treatment to the incoming organic matters - saving the energy, reducing the CO₂ production and optimizing management costs
• Ensure that the treatment process is in optimal working condition
• Ensure that the effluent complies with the appropriate regulations in order to avoid damage to the environment

Figure 1. The dilution procedure. (Landis, T. D.; Dumroese, R. K.2006)

BOD Determination Methods

At BOC Sciences, our BOD testings can be divided into three measurable categories: total BOD (tBOD), soluble BOD (sBOD), and carbonaceous BOD (CBOD). And we employ the dilution method to measure BOD:

• Firstly, dilution water is prepared by adding inorganic nutrients (containing a phosphate buffer solution, a magnesium sulfate solution, a calcium chloride solution, and a ferric chloride solution) and buffer salts to purified water. A known amount of microbial seeds may also need to be added if the sample does not contain sufficient amounts of bacteria, or contains compounds that are toxic to bacteria (e.g. chlorinated effluent)
• Then, different dilution levels of the sample water are prepared using the dilution water. The BOD bottles are filled to the top, capped and sealed
• They are incubated at 20°C in the dark for 5 days, and the level of dissolved oxygen is measured before and after the 5-day incubation period. Dilutions are determined by estimating the amount of BOD in the sample using the measured chemical oxygen demand (COD) or another suitable surrogate. The DO of the sample is measured initially after mixing the solution and again after five days for the BOD, or after one day for the BOD test. The difference between these two values, corrected for dilution and blank, is the BOD value. BOD test results are expressed in mg/L of dissolved oxygen